In recent years, application of a secondary battery such as a lithium ion battery is rapidly increased in a power storage module for storing power, a storage battery for a car, and the like combined with a new energy system such as a solar cell or wind power generation. A battery system connected to one or more power storage modules is used in order to generate large output. The power storage module is formed by housing, in an outer case, one or more battery blocks which are battery packs, for example. The battery block is formed by connecting a plurality of unit batteries, namely, exemplary power storage elements (also referred to as electric cells or cells. In the following description, simply referred to as a battery cell as necessary).
Technologies related to a power storage module are disclosed in Patent Documents 1 to 5 below.